Kayo is Shougen's Model Dolphin Initiator. She has an IQ of 210 but is unsuited to front-line battles. During her mission to eliminate the Hiruko pair, she was separated from Shougen and met Rentarou.

As she protected the area from Gastrea led by the Hiruko pair's battle, the amount of Gastrea virus in her body exceeded the critical value, thus she requested Rentarou to shoot her while she's still human.